A wireless communication system includes a Base Station (BS) and one or more User Equipments; (UEs). The user equipment can be fixed or mobile and can be referred to as another terminology, such as a Mobile Station (MS), a User Terminal (UT), a Subscriber Station (SS), or a wireless device. In general, the base station refers to a fixed station that communicates with the user equipments, and it can be referred to as another terminology, such as a Node-B, a Base Transceiver System (BTS), or an access point. Hereinafter, uplink (UL) transmission refers to transmission from a user equipment to a base station, and downlink (DL) transmission refers to transmission from a base station to a user equipment.
A wireless communication system has a cell structure in order to configure an efficient system. The cell refers to an area subdivided from a wide area in order to efficiently use the frequency. In general, a base station is deployed at the center of a cell in order to relay user equipments, and the cell refers to a service area in which one base station is deployed.
The next-generation multimedia wireless communication systems which are recently being actively researched are required to process various pieces of information, such as video and wireless data, in addition to the early voice-centered service with a higher data transmission rate.
Orthogonal Frequency Division Multiplexing (OFDM) having a high data transmission rate has recently been in the spotlight. The OFDM is a multi-carrier modulation scheme for dividing a frequency band into a number of orthogonal subcarriers and transmitting data in the divided frequency bands. Orthogonal Frequency Division Multiple Access (OFDMA) is a scheme for providing multiplexing of a multi-user by combining Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), or Code Division Multiple Access (CDMA) with OFDM.
If neighbor cells of the OFDM/OFDMA systems use the same subcarrier in a multi-cell environment, it can become a cause of interference to users. This phenomenon is called inter-cell interference. In particular, the inter-cell interference becomes a big problem to user equipments placed near the boundaries of the cells. In downlink transmission, a user equipment placed near the boundary of a cell is subject to strong interference resulting from neighbor cells. In uplink transmission, a user equipment placed near the boundary of a cell provides strong interference with neighbor cells and has a low transmission rate because of the loss of a path in a serving cell.
To reduce such inter-cell interference, neighbor cells can use different subcarriers. This method is however problematic in that radio resources that can be used by the base stations of respective cells are reduced.
A coordinated multi-cell method has been proposed in order to reduce such inter-cell interference in a multi-cell environment. If the coordinated multi-cell method is used, the performance of communication of a user equipment placed near the boundary of a cell can be improved. Discussions on a method of transmitting and processing data using the coordinated multi-cell method are in progress.